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Journal Identification = MRH Article Identification = 0424 Date: August 10, 2017 Time: 1:46 pm
Magnesium Research 2017; 30 (2): 61-70 ORIGINAL ARTICLE
Effect of magnesium supplementation
on muscular damage markers in
basketball players during a full
season
Alfredo Córdova Martínez1, Diego Fernández-Lázaro1, Juan Mielgo-Ayuso2, Jesús
Seco Calvo3, Alberto Caballero García4
1University of Valladolid, Faculty of Physical Therapy, Department of Biochemistry and
Physiology, Campus de Soria, 42003 Soria, Spain; 2ElikaEsport, Nutrition, Innovation and
Sport, Gipuzkoa, Spain; 3University of León, Institute of Biomedicine (IBIOMED), León,
Spain; 4University of Valladolid, Faculty of Physical Therapy, Department of Anatomy, Cam-
pus de Soria, 42003 Soria, Spain
Correspondence: Diego Fernández Lázaro. Facultad de Fisioterapia, Campus Universitario de Soria, 42003 Soria,
Spain.
<diego.fernandez.lazaro@uva.es>
Abstract. Although it has been widely accepted that Mg has a positive effect
on muscle function, studies on the efficacy of Mg supplementation in young
athletes have generated contrasting results. The aim of this work was to exam-
ine the effect of Mg supplementation on muscular damage markers and the
association between serum Mg levels with these muscular markers. Twelve
elite male basketball players (PB) from a team of Spanish Professional Bas-
ketball League and a control group (CG) comprising twelve university students
who practiced regularly recreational basketball and competed in minor univer-
sity leagues participated in this study. The athletes were supplemented with
400 mg/day of Mg, in the form of Mg lactate. Blood samples were taken four
times during the season, each separated by eight weeks: T1: October, T2: Decem-
ber, T3: March, and T4: April. Serum Mg concentrations showed a significant
decrease in T3 (1.56 ±0.03 mg/dL), with respect to T1 (1.69 ±0.04 mg/dL) and
T2 (1.69 ±0.04 mg/L). At the end of the study, serum Mg concentration was sig-
nificantly higher (T4: 1.79 ±0.06 mg/dL) than at T3. Levels of muscle damage
parameters remained the same during the entire season (P>0.05), except for
creatinine, which significantly decreased after T2, and then increased signifi-
cantly in T3 and T4 compared to T2. In conclusion, these results suggest that
the supplementation with Mg during the season of competition may prevent
associated tissue damage.
Key words: Mg supplementation, serum Mg, basketball, muscular damage
Magnesium (Mg) is a cation closely involved
in different metabolic and physiological processes
related with muscular performance [1]. Mg is
essential for energy metabolism, transmembrane
transport, and muscle relaxation and contraction
[2]. On the basis of these physiological effects, Mg
has been studied as an ergogenic aid for athletes
[3].
Some authors have described that exercise may
increase the demand for Mg and/or Mg loss, poten-
tially leading to hypomagnesemia, and can result
in muscle weakness, neuromuscular dysfunction,
doi:10.1684/mrh.2017.0424
61
To cite this article: Córdova Martínez A, Fernández-Lázaro D, Mielgo-Ayuso J, Seco Calvo J, Caballero García A. Effect of
magnesium supplementation on muscular damage markers in basketball players during a full season. Magnes Res 2017; 30(2):
61-70 doi:10.1684/mrh.2017.0424
Journal Identification = MRH Article Identification = 0424 Date: August 10, 2017 Time: 1:46 pm
A. C ´
ORDOVA MART´
INEZ, ET AL.
and tetany, all affecting the physical performance
and/or health status [2, 4, 5]. Zorbas et al. [6] noted
that hypokinesia provokes a less utilization of Mg
accompanied with decrease in muscular Mg lev-
els, even after Mg supplementation. Brilla and
Haley [7] reported that supplementation with Mg
increases muscle strength and power. However,
Terblanche et al. [8] observed that marathon run-
ners with adequate Mg status did not improve
their running performance or skeletal muscle
function. Despite these discordant results, the
findings suggest that Mg supplementation can
be considered as an ergogenic aid with beneficial
effect on the physiological function and/or perfor-
mance when Mg status is normal [3, 9].
Stendig-Lindberg et al. [10] measured blood
Mg and creatine kinase (CK) activity in partici-
pants who completed a 120-mile hike and found
an increase in both at 24 h postexercise. Because
CK is released from damaged skeletal muscle
after exercise [11], the authors suggested that the
increased Mg levels 24 h postexercise may reflect a
release from damaged tissue. Significantly inverse
correlation exists between blood concentration of
this enzyme released from the muscle and athletic
performance [4, 12]. Other authors have recently
suggested that Mg status is related to tissue and
cell protection in athletes [13, 14].
Exercise stress leads to a proportional increase
in stress hormone levels, for example, cortisol
(C), and concomitant alterations of immunity
[15]. In addition, low plasma Mg concentrations
and the subsequent disruption in intracellular
Mg homeostasis may play a role in activating
inflammatory response [16]. However, regular and
moderate exercise has been reported to improve
the ability of the immune system to protect from
infection [17].
There is an association between Mg and
immune function, in particular based on find-
ings that Mg deficiency leads to inflammation
[18]. The activation of immune cells, such as
monocytes, macrophages, and polymorphonuclear
neutrophils, that synthesize a variety of media-
tors, induces inflammatory events [19, 20].
Although it has been widely accepted that Mg
has a positive effect on muscle function, studies
on the efficacy of Mg supplementation in young
athletes have generated contrasting results [7, 8].
Based on the existing data [3, 9, 21], and our
experience, it appears that most athletes do not
consume adequate amounts of Mg in their diets. In
addition, the analyses of diets may overestimate
true dietary intake; thus, diet supplementation
with this mineral may be justified.
In view of this information, the aim of this
study was to examine the effect of Mg supple-
mentation on muscular damage markers and the
association between serum Mg levels with these
markers.
Material and methods
Participants
Twelve elite male basketball players from a team
of Spanish Professional Basketball (PB) League
have participated (25.3 ±4.4 years; 198 ±9.9 cm,
96.8 ±13 kg; 56.5 ±7.7 mL·kg-1·min-1 )inthe
study. The control group (CG) comprised twelve
university students who practiced regularly
recreational basketball and competed in minor
university leagues (22 ±3.8 years; 178 ±8.6 cm;
78.3 ±8.6 kg; 47 ±6.3 mL·kg-1·min-1 ). None of the
athletes smoked, drank alcohol regularly, or were
taking any medication known to alter hormonal
response. Concomitant pathology was excluded
by additional record and medical examination.
These sportsmen did not receive supplements,
except a multivitamin complex during the sea-
son, and all performed the same training
program and matches. The PB group was sup-
plemented with 400 mg/day of Mg in the form
of lactate Mg. The CG was not supplemented
with Mg.
The PB group followed a standardized diet
defined by the doctor and the dietician/nutritionist
of the team. Diet schedule was planned in Septem-
ber, during the days prior to the start of preseason
training. The dietician/nutritionist indicated the
type and quantity of total energy intake in func-
tion of requirements at each moment of the
competition. Intake was controlled by a dietary
record, for 3-7 days, at each training period.
Calculated intake of Mg/1,000 kcal was in aver-
age 217 ±4.6 mg, considering the full season.
The content of Mg was determined using the
food tables established by the Spanish Society of
Dietetics and Nutrition [22].
The PB group trained daily in 2 sessions:
a morning session that consisted of a 2-hour
gym workout and an afternoon session of 3-
hour basketball practice. This training program
was followed daily except on the days of official
62
Journal Identification = MRH Article Identification = 0424 Date: August 10, 2017 Time: 1:46 pm
Serum Mg during a full season in basket players
matches played during the season and, therefore,
during the study (2 matches per week, Wednes-
days and Sundays).
Protocol and assessment plan
Protocol and assessment plan was done in 4 spe-
cific time points, each 8 weeks during the season:
(a) T1: October (in preseason, at the end of first
mesocycle training); (b) T2: December (at the end
of second mesocycle training: preseason + specific
phase); (c) T3: March (at the end of competitive
phase I: coincident with King’s Cup competition);
and (d) T4: April (at the end of competitive phase
II: coincident with the final of the ACB and Euro
league regular seasons). The CG participants were
required in the same day to attend the laboratory
(8:00-8:30 a.m.), at the same time as those in the
PB group.
Antecubital venous blood samples were col-
lected from all the players in basal conditions
after overnight fasting and 36 hours after the last
training or match day to avoid acute effects of
exercise on hormones. The players arrived at the
laboratory at 8:30 in the morning, and after a 30-
minute rest in a comfortable seat, blood samples
were taken. Blood was collected by antecubital
venipuncture with Vacutainer system (10 mL to
serum tubes with gel and clot activator; 5 mL and
3 mL to tubes with EDTA). Serum was separated
from blood cells and stored at -20◦C until further
analyses.
The use of control group (CG) permits a com-
parison with PB group before the start of the
experiment. Later, when the PB group partici-
pants are training and competing, this comparison
is not possible because the physical activity was
not the same, that is, PB 5 h/day and CG
5 h/week. In addition, we do not compare the
results obtained by PB group in T1-T4 periods
with T0 because the number of hours and intensity
of training were different.
The study was designed in accordance with the
Declaration of Helsinki of the World Medical Asso-
ciation recommendations for clinical research, and
the protocol was reviewed and approved by the
ethics local committee in the university.
Blood analyses
Serum Ca and Mg were determined with a Perkin
Elmer 272 flame atomic absorption spectrom-
eter (FAAS) [PerkinElmer, Inc. Waltham, MA
(USA)] in flame emission mode. White blood cell
and platelet counts were determined on a Coul-
ter Counter (model MAX-M) [Beckman Coulter.
New Jersey, NJ (USA)]. Serum concentrations
of creatinine, urea, creatine kinase (CK), lactate
dehydrogenase (LDH), aspartate transaminase
(AST), alanine transaminase (ALT), aldolase
(ALD), and total proteins (TP) were measured
at each time point (T0, T1, T2, T3, and T4).
These biochemical parameters were measured
using coupled enzyme reactions on an automatic
autoanalyzer [Hitachi 917, Tokyo, Japan]. Myo-
globin (Mb) was assessed by chemiluminescence
reaction enzyme immunoassay “sandwich” of two
points (Myoglobin ELISA Kit, MEXLAB. Zapopan,
Jalisco, Mexico).
Serum total testosterone (TT) levels were mea-
sured by ELISA (DRG testosterone ELISA kit®,
DRG Instruments GmbH, Marburg/Lahn, Ger-
many). Free testosterone (FT) was obtained by
the formula described and validated by Ver-
meulen et al. [21]. Cortisol (C) concentrations
were measured by an enzyme-linked fluorescent
assay with the aid of a multiparametric analyzer
(Minividas®, Biomerieux, Marcy l’Etoile, France),
using as substrate 4 methylumbelliferone capable
of a fluorescent emission at 450 nm, after stimula-
tion at 370 nm. TT, FT, and cortisol were expressed
in nMol·L-1. TT/C and FT/C ratios were calculated
from TT, FT, and cortisol molar concentrations.
All biochemical analyses were carried out in an
official hospital laboratory with the corresponding
strict control measures.
Percent changes in plasma volume (%PV)
were calculated using Van Beaumont’s equation
[23]. The values of hematological and biochem-
ical markers were adjusted for plasma volume
changes using the following formula [25]:
Corrected value =Uncorrected value
×100+%PV/100
Statistical analyses
Data were expressed as mean ±standard error
of the mean. The Shapiro-Wilk test was used.
After checking the normal distribution, one-way
repeated measures ANOVA was carried out for
all biochemical parameters (minerals, white blood
cells, muscle damage, and stress) by Greenhouse-
Geisser test to check if there were significant
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A. C ´
ORDOVA MART´
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variations among parameters in the different
phases of the study. To determine differences
among different periods of study, post hoc Bon-
ferroni multiple comparisons test was applied.
Bivariate correlations for changes in Mg with
blood cells, muscle damage, and stress parameters
during season (T1-T4) were performed using
Pearson rank order correlation test according the
following calculation:
(T1-T4)=((T4-T1)/T1)×100
Statistical analyses were performed by IBM
Statistical (SPSS Version 22) and Graphpad
Prism 5 software (Version 5.2) packages. A value
of P<0.05 was considered as significant.
Results
As shown in table 1, serum Mg concentrations
between CG and PB group were not significantly
different. Figure 1 shows the serum Mg and Ca
concentrations in the 4 periods of season. Serum
Mg concentration significantly decreased in T3 in
comparison to T1 and T2. However, at the end
of the study (T4), Mg concentration was signifi-
cantly higher than T3. Serum Ca concentration
in T1 presented significantly lower value than the
other 3 points. Moreover, T2 showed lower level of
serum Ca concentration than T3 and T4.
The levels of muscle damage parameters in the
PB group remained the same during the entire
season (P>0.05) (table 2), except for creatinine,
concentrations of which significantly decreased
after the second mesocycle in December, and then
increased significantly in T3 and T4 in comparison
with T2 level. In table 2, we also show the %PV
changes between T1 and other periods.
Table 3 shows blood hormone parameters in the
four test points during the basketball season. Cor-
tisol levels were significantly lower at the end of
the second mesocycle in December and at the end
of the third mesocycle in April; this was coincident
with the end of the ACB and Euro league reg-
ular season. However, cortisol remained at high
Table 1. Biochemical, mineral, hormonal, and hematological data in the control group (CG) and the
professional basketball players (PB) group 15 days before the start of the study.
Parameter Group Mean ±SEM Parameter Group Mean ±SEM
Creatinine (mg/dL) CG 0.95 ±0.14 Cortisol (C) (nmol/L) CG 14.58 ±4.53
PB 1.20 ±0.09 PB 22.19 ±3.44
Urea (mg/dL) CG 30.64 ±7.27 Total Testosterone
(TT) (nmol/L)
CG 4.95 ±1.66
PB 37.58 ±6.97 PB 6.48 ±0.69
Creatine kinase
(CK) (U/L)
CG 200.08 ±69.62 TT/C CG 0.339 ±0.004
PB 292.00 ±87.07 PB 0.292 ±0.006
Myoglobin
(Mb) (ng/mL)
CG 30.98 ±11.11 Platelets (×103/L3)CG 238.71 ±24.61
PB 35.84 ±2.95 PB 227.58 ±33.69
Lactate dehydrogenase
(LDH) (U/L)
CG 159.79 ±17.80 WBC (×103/L) CG 5.66 ±1.09
PB 380.08 ±50.92 PB 6.92 ±1.86
Aspartate transaminase
(AST) (U/L)
CG 23.50 ±6.12 Neutrophils (%) CG 2.62 ±0.78
PB 25.83 ±4.30 PB 41.24 ±8.29
Alanine transaminase
(ALT) (U/L)
CG 16.36 ±6.77 Lymphocytes (%) CG 2.31 ±0.42
PB 22.00 ±3.07 PB 37.30 ±8.51
Total proteins
(g/dL)
CG 7.53 ±0.51 Monocytes (%) CG 0.50 ±0.12
PB 7.61 ±0.19 PB 7.31 ±0.21
Aldolase (ALD)
(U/L)
CG 4.93 ±0.33 Eosinophils (%) CG 0.19 ±0.14
PB 5.37 ±0.41 PB 2.44 ±1.16
Magnesium (Mg)
(mg/L)
CG 2.07 ±0.18 Basophils (%) CG 0.04 ±0.02
PB 1.83 ±0.29 PB 0.71 ±0.41
Calcium (Ca)
(mg/dL)
CG 9.99 ±0.55 Hematocrit (Hct) % CG 48.05 ±2.14
PB 9.1 ±0.57 PB 46.76 ±2.46
64
Journal Identification = MRH Article Identification = 0424 Date: August 10, 2017 Time: 1:46 pm
Serum Mg during a full season in basket players
2.0 11.0
10.5
10.0
9.5
9.0
8.5
C
Mg Ca
a, b
a, b
a
a, b
1.9
1.8
1.7
1.6
1.5
1.4
Data are expressed as mean ± standard error of the mean (SEM). N=12
Significant differences among period of study by Bonferroni’s test a,bp<0.01: avs. T1. bvs. T2, cvs. T3.
T1
T2
T3
T4
T1
T2
T3
T4
mg/dL
mg/dL
Figure 1. Serum magnesium (Mg) and calcium (Ca) concentrations in professional basketball (PB)
players during a full season. (T1: October; T2: December; T3: March; T4: April). Data are expressed as
mean ±standard error of the mean (SEM) (n= 12). Significant differences among the periods of study
by Bonferroni’s test a,bP<0.01: aversus T1; bversus T2; cversus T3.
Table 2. Biochemical data and changes of plasmatic volume (%PV) in function of hematocrit (Hct)
in professional basketball players (PB) during a full season (T1: October; T2: December; T3: March;
T4: April).
T1 T2 T3 T4
Creatinine (mg/dL) 1.25 ±0.03 1.14 ±0.02a1.30 ±0.03b1.25 ±0.02b
Urea (mg/dL) 42.33 ±1.81 39.50 ±2.62 41.83 ±1.77 43.75±2.74
Creatine kinase (CK) (U/L) 621.7±177.2 438.3 ±52.8 391.8 ±59.5 545.9 ±99.5
Myoglobin (Mb) (g/mL) 36.29 ±9.64 34.21 ±2.22 35.38 ±2.46 37.78±2.48
Lactate dehydrogenase (LDH) (U/L) 373.9±15.5 374.9 ±15.5 375.0 ±15.4 383.5 ±18.7
Aspartate transaminase (AST) (U/L) 40.67 ±5.69 33.17 ±2.15 31.42 ±2.04 34.58 ±3.37
Alanine transaminase (ALT) (U/L) 30.17 ±4.37 29.00 ±1.82 27.00 ±1.53 24.83 ±1.55
Total proteins (TP) (g/dL) 7.39 ±0.12 7.29 ±0.12 7.32 ±0.08 7.30 ±0.08
Aldolase (ALD) (U/L) 10.62 ±1.90 7.17 ±0.43 7.67 ±0.69 7.03 ±0.52
T0-T1 T1-T2 T1-T3 T1-T4
%PV <1 7.10 8.05 7.06
Data are expressed as mean ±standard error of the mean (SEM). Significant differences among the periods of study
by Bonferroni’s test a,bP<0.01: aversus T1; bversus; T2. cversus T3 (%PV): percent changes of plasma volume.
levels at the end of the first mesocycle training in
October and at the end of King’s cup in March (T3).
Total testosterone (TT) concentration increased
significantly in T2, T3, and T4 with respect to T1
(table 3). This increase was higher at the end of the
King’s Cup in T3. Free testosterone (FT) concen-
tration was significantly lower in T3 compared to
other studied periods. TT/C ratio increased signif-
icantly in T2, T3, and T4 in comparison to T1.
However, at the end of King’s Cup in T3, this
decreased TT/C ratio remained in T4. The FT/C
ratio significantly decreased during the season; a
detailed description of each of the periods showed
that the FT/C ratio was higher in T2 than in the
other control points, with the lowest value in T3,
i.e. at the end of King’s Cup.
Table 4 shows white blood cell count and hema-
tocrit (Hct) during season. Platelets’ number was
not significantly affected during the study period.
WBC count showed statistically higher value at
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Table 3. Plasma hormones in professional basketball players (PB) during a full season (T1: October;
T2: December; T3: March; T4: April)
P
Cortisol (C) (nmol/L)
T1 623.2 ±48.2
P<0.05
T2 451.9 ±27.2a
T3 624.7 ±33.7b
T4 487.5 ±32.0a
Total testosterone (TT) (nmol/L)
T1 19.44 ±2.13
P<0.001
T2 23.90 ±2.08a
T3 26.76 ±2.25a,b
T4 22.30 ±1.67a
Free testosterone (FT) (nmol/L)
T1 0.093 ±0.006
P<0.05
T2 0.116 ±0.014
T3 0.074 ±0.008a,b
T4 0.082 ±0.015
TT/C
T1 0.034 ±0.005
P<0.001
T2 0.054 ±0.005a
T3 0.043 ±0.003b
T4 0.047 ±0.003a
FT/C ×103
T1 0.157 ±0.016
P<0.05
T2 0.268 ±0.039
T3 0.123 ±0.014b
T4 0.174 ±0.032
Data are expressed as mean ±standard error of the mean (SEM). Significant differences among the periods of study
by Bonferroni’s test a,bP<0.01: aversus T1; bversus T2.
Table 4. Hematological data of professional basketball (PB) players during a full season. (T1: October;
T2: December; T3: March; T4: April)
T1 T2 T3 T4
Platelets (×103/L3) 222.75 ±12.78 216.25 ±8.60 216.50 ±10.42 214.83 ±10.52
WBC (×103/L) 5.25 ±0.26 5.25 ±0.23 5.30 ±0.32 6.13 ±0.34a,b
Neutrophils (%) 46.53 ±3.76 43.51 ±3.92 44.93 ±2.93 43.98 ±3.28
Lymphocytes (%) 39.88 ±3.36 44.58 ±4.04 42.03 ±2.43 42.97 ±3.11
Monocytes (%) 6.98 ±0.32 7.08 ±0.57 6.98 ±0.41 7.11 ±0.54
Eosinophils (%) 2.83 ±0.51 2.62 ±0.49 2.28 ±0.35 2.49 ±0.30
Basophils (%) 1.16 ±0.13 0.89 ±0.13 0.94 ±0.08 0.95 ±0.11
Hematocrit (Hct) (%) 46.50 ±1.99 44.80 ±2.06 44.57 ±1.70 44.82 ±2.55
Data are expressed as mean ±standard error of the mean (SEM). Significant differences among the periods of study
by Bonferroni’s test a,bP<0.01: aversus T1; bversus T2.
the end of the season (T4) than in T1 and T2. The
percent distribution of different types of leuko-
cytes or hematocrit was not significantly different
among various periods. In table 1, we also show
the %PV, which revealed a change with respect
to T1 (start of study). Three time points were ana-
lyzed: T1-T2 (7.10%), T1-T3 (8.05%), and T1-T4
(7.06%).
66
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Serum Mg during a full season in basket players
50
Δ (T1 - T4)
Δ (T1 - T4)
Mg
Mg
40
30
30
20
20
10
r=0.590
p=0.044
r=0.617
p=0.033
10
0
0
-10
-10
-20
2
0
-2
-4
-6
-8
4
-20
3020100-10-20
LeucocytesTotal proteins
Figure 2. Bivariate correlations among magnesium (Mg) and leukocytes and total protein changes
during a full season (T1-T4).
Bivariate correlations among changes during
season in Mg concentration and white blood cells
count, muscle damage, and stress parameters
were analyzed. Significantly positive correlations
(P<0.05) between Mg concentration and leuko-
cytes, and between serum Mg and total protein
concentrations, were observed (figure 2).
Discussion
In the current study, we aimed at investigating
the changes in muscular damage markers along
the season and their relation with serum Mg
changes in basketball players. These sportsmen
received regularly a supplementation of 400 mg of
Mg/day. Our main findings under these conditions
were that none of the athletes showed significant
changes in Mg levels or change in the muscular
damage markers along the season.
According to the Spanish Society of Dietet-
ics and Nutrition [22], 400 mg/day of Mg is the
suggested intake recommendation for adult men.
Similarly, in the United States (US) [26], the
recommended daily intake of Mg for adult men
between 19 and 30 years is 400 mg/day, and for
adults between 31 and 50 years, it is 420 mg/day.
A large number of nutrition and performance
researches report that most athletes do not con-
sume adequate amounts of magnesium in their
diets [3, 9, 21, 27-29]. In this context, sport nutri-
tionists and dieticians must be aware of potential
differences between calculated and real content of
vitamins and minerals in the analyzed daily food
rations of athletes [30].
Our athletes followed a standardized
and controlled diet supervised by the dieti-
cian/nutritionist of the team according to rules
of sport nutrition, which is based on carbohy-
drate, lipid, and protein content. The mean
Mg consumption in the diet in our study was
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A. C ´
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INEZ, ET AL.
217 ±4.6 mg/1,000 kcal, which exceeded the
widely recognized dietary recommendations.
However, Czaja et al. [21] have indicated that
the specific RDA for athletes is not established.
The sportsmen, who limit the variety of the con-
sumed food or energy requirement in their diet,
are exposed to the risk of insufficient intake of
microelements and vitamins [21, 31]. Hassapidou
et al. [32] studied elite Greek basketball players
during competitive season and reported that
most athletes do not follow an adequate dietary
intake. Considering the condition of professional
sportsmen and taking into account the possible
deleterious consequences of Mg deficiency, we
consider that supplementation of Mg may be of
interest for this population.
In our study, we choose to supplement athletes
with 400 mg of Mg/day. Previously, Mg supple-
mentation was used by elite German and Polish
athletes [21, 34]. The Polish elite athletes [21]
were supplemented daily with 284 ±58 mg of Mg.
In other studies, with volleyball players, Setaro et
al. [33] used 350 mg of Mg/day supplements. In
addition, in the review by Newhouse et al. [30], all
studies showed positive effects on sports perfor-
mance with magnesium supplementation ranging
from 240 to 413 mg/day. Veronese et al. [28]
showed that oral supplementation with 400 mg
Mg as Mg oxide for 12 weeks had a significant pos-
itive effect on physical performance. In our study,
supplementation with organic salt of Mg, that is
lactate, my offer better conditions for the absorp-
tion of Mg [36].
It is important to consider that all systems, mus-
culoskeletal, nervous, immune, and metabolic, are
stressed by exercise and competition, and there-
fore the recovery strategies postexercise are very
important for sportive success. Mg has a funda-
mental role in muscle function and is essential for
energy metabolism, transmembrane transport,
and muscle relaxation and contraction [2, 26].
However, previous studies on the efficacy of Mg
supplementation in young athletes have gener-
ated contrasting results [7, 8, 37, 38]. Differences
in Mg status may be the reason for these dif-
ferent findings. It has been suggested that Mg
supplementation might be only efficient in Mg-
deficient people [4]. In our study, all athletes
(n= 12) had serum Mg below the normal values
during measurement at point T3. This point was
in a competitive period of high effort demand as
is the King’s cup, with 3 games in 5 days. The
main feature of our study is that serum Mg levels
were maintained high along the season, and even
increased in the last control. When we corrected
(in function of %PV), the serum Mg levels are in
the normal range. It should be borne in mind that
some authors have indicated that a transient shift
of Mg from the extracellular fluid to skeletal mus-
cle is the proposed mechanism for the decrease in
Mg during exercise [39-41]. Muscle exercise leads
to a slow increase in muscle Mg content, which is
paralleled by a decline in plasma Mg concentra-
tion. This suggests that the reduction in serum
Mg observed during exercise may be, in part, a
function of redistribution of serum Mg into the
working muscle. These Mg shifts into contract-
ing muscle may a function of increased metabolic
need [39-41]. In this study, only limited changes
in serum Mg were observed, which were probably
related to adequate Mg supply in the diet and as
supplement.
Some muscular enzymes and proteins are
considered as markers of muscle metabolism
intensity and damages [11, 42]. Previously, we
observed that muscle damage is associated with
increase in plasma CK, alanine aminotransferase
(ALT), and aldolase (ALD) levels, which is a
routine biochemical evaluation in the diagnosis
of muscle disease [41, 42]. This study supports
that magnesium supplementation may prevent a
drop in serum magnesium level and an increase
in the level of biochemical markers of mus-
cular damage in basketball players along the
season.
In T3 (3 matches in 5-day tournament), we
observed a decrease in FT and an increase in cor-
tisol as a consequence of failing to meet recovery
periods to return to baseline values [44]. However,
our athletes with adequate training, nutrition,
and supplementation maintained a good anabolic-
catabolic balance, as was reported in other studies
[43].
The main limitation of this study is the absence
of a similar control group without Mg supplemen-
tation. To have professional players as controls
was not easy, because they are few and placed
in different cities with particular training (differ-
ent coaches) and nutritional habits. However, at
the beginning of the study, groups CG and PB
had similar values of biochemical and hematolog-
ical parameters. We also used as reference groups
athletes from other studies reporting changes in
markers of muscle damage indices in soccer, bas-
ketball, volleyball, and handball games at an elite
competitive level [42, 46, 47]. However, the effect
68
Journal Identification = MRH Article Identification = 0424 Date: August 10, 2017 Time: 1:46 pm
Serum Mg during a full season in basket players
of supplementation was not reported in these
studies.
In conclusion, these results show that supple-
mental Mg in elite athletes, during a competition
season, could exert a protective effect on the mus-
cle. This occurred without significant changes in
cortisol and anabolic hormone levels.
Disclosure
Financial support: none. Conflict of interest: none.
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